Can a 13-year-old develop rickets?

Can Rickets Occur in a 13-Year-Old?

Yes, rickets can absolutely occur in a 13-year-old adolescent, and this age group represents a distinct clinical entity with different etiological factors compared to infantile rickets.

Epidemiology and Clinical Presentation in Adolescents

Adolescent rickets is well-documented and presents differently than the classic infantile form:

• Prevalence in adolescents is substantial, with one study documenting a rate of 68 per 100,000 children-years in the 10-15 year age group 1
• Female adolescents are disproportionately affected, representing 20 of 21 cases in one case series, likely due to cultural practices limiting sun exposure 1
• Symptomatic presentation differs from infants: carpopedal spasms (hypocalcemic tetany) and diffuse limb pains are the most common presentations, rather than the bowing deformities typical in younger children 1
• Radiological evidence may be absent in many adolescent cases despite biochemical and clinical rickets, making diagnosis more challenging 1

Etiological Differences Between Age Groups

The pathophysiology of rickets varies significantly between young children and adolescents:

In Adolescents (like your 13-year-old patient):

• Vitamin D deficiency is the primary driver, with inadequate sun exposure being critical 2
• Calcium deficiency is universal but insufficient alone to cause disease 2
• Treatment requires both calcium AND vitamin D for healing, unlike younger children 2
• Adolescents showed no response to calcium supplementation alone but achieved complete healing in 3-9 months when vitamin D was added 2

In Young Children (under 5 years):

• Calcium deficiency may be more important than vitamin D deficiency in some populations 2, 3
• Children can heal completely with calcium supplementation alone within 3 months 2
• Some children with rickets have 25-hydroxyvitamin D levels above the rachitic range (>25 nmol/L), suggesting calcium deficiency as the primary etiology 2

Risk Factors Specific to Adolescents

Key risk factors to assess in a 13-year-old:

• Limited sun exposure (<60 minutes per day), particularly in females due to cultural dress practices or indoor lifestyle 1
• Inadequate dietary calcium intake (typically <300 mg/day vs. recommended 1,250 mg/day for ages 9-18) 4, 2, 1
• Inadequate dietary vitamin D intake from fortified foods 1
• Dark skin pigmentation combined with limited sun exposure 4
• Prolonged exclusive breastfeeding history without supplementation during infancy 4

Diagnostic Approach

Biochemical findings in adolescent rickets:

• Hypocalcemia is present in approximately 90% of cases 1
• Elevated serum alkaline phosphatase is universal and the most reliable marker 1
• Hypophosphatemia occurs in about 43% of cases 1
• Elevated parathormone when measured 1
• Reduced 25-hydroxyvitamin D concentrations when measured 1
• Radiological changes may be subtle or absent in adolescents, unlike the florid metaphyseal changes seen in infants 1

Treatment Recommendations for Adolescent Rickets

For nutritional rickets in a 13-year-old, combined therapy is essential:

• Vitamin D supplementation is mandatory, as adolescents do not respond to calcium alone 2
• Calcium supplementation (1 gram daily) must be given concurrently 2
• Expected healing time is 3-9 months (mean 5.3 months) with combined therapy 2
• For vitamin D-resistant rickets, ergocalciferol 12,000-500,000 USP units daily may be required under close medical supervision 5

Differential Diagnosis Considerations

While nutritional rickets is most common, consider genetic forms in adolescents:

• X-linked hypophosphatemia (XLH) represents ~80% of hereditary hypophosphatemic rickets and can present with symptoms developing after age 2 years 4, 6
• Vitamin D-dependent rickets type 1A should be suspected if the patient fails to respond to standard vitamin D supplementation 7
• Hereditary hypophosphatemic rickets with hypercalciuria (HHRH) presents with hypercalciuria before treatment, distinguishing it from other forms 4, 7

Clinical Pitfalls to Avoid

• Do not assume rickets only occurs in infants and toddlers—adolescents are at significant risk, especially females with limited sun exposure 1
• Do not rely solely on radiographs—biochemical evidence (elevated alkaline phosphatase, hypocalcemia) may be present without radiological changes 1
• Do not treat adolescent rickets with calcium alone—vitamin D supplementation is essential for healing in this age group 2
• Do not overlook hypocalcemic tetany (carpopedal spasms) as a presenting symptom in adolescents 1